SDM-AO4A 4-Channel Analog Output Module
Increases Available CAO Ports
Provides high resolution and high accuracy
weather applications supported water applications supported energy applications supported gas flux and turbulence applications supported infrastructure applications supported soil applications supported


The SDM-AO4A module increases the number of continuous analog outputs available to a datalogger. These outputs are used for proportional control or driving strip charts.

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Benefits and Features

  • Increases the number of CAO ports available to the data logger
  • Supports both ±5 V and 0 to 10 V modes, allowing the module to be used in more applications
  • Includes a choice of synchronous and sequential operation


Technical Description

The SDM-AO4A is designed to output four continuous voltages at levels set by a Campbell Scientific data logger. The data logger enables individual modules through an addressing scheme; multiple SDMs (in any combination) can be connected to one data logger. After a module is enabled, it operates independently of the data logger until additional commands are received or results are transmitted.

The SDM-AO4A can be operated in ±5 V mode or 10 V mode. In each of these modes, the SDM-AO4A can operate synchronously or sequentially. In synchronous mode, all channels are set at the same time.


Function Increases the number of continuous analog output (CAO) ports available to a data logger. CAOs are used for proportional control or driving strip charts.
Number of Channels 4
Operating Temperature -40° to +60°C
Voltage Range ±5 V or 0 to 10 V
Resolution 167 µV
Operating Voltage 12 Vdc nominal (9.6 to 16 Vdc)
Maximum Output Current
  • 50 mA (per channel)
  • 100 mA (total)
Overcurrent Shutdown Point 130 mA ± 15 mA
Dimensions 13.46 x 8.51 x 2.41 cm (5.3 x 3.35 x 0.95 in.)
Weight 175 g (6.2 oz)

Accuracy with 20 kΩ Load (maximum)

25°C ±(0.05% of |Vout(V)|+500µV)
-40° to +60°C ±(0.1% of |Vout(V)|+500µV)

Additional Full-Scale Error with 50 mA Load

±5 V Mode -1.3 mV (typical)
0 to 10 V Mode -1.5 mV (typical)

Typical Current Drain (±5 V Mode)

No load, Vout=0, Vsupply=12V 11 mA
No load, Vout=fullscale, Vsupply=12V 13 mA
With load, Vsupply=12V 13 mA + load
Power Down Mode, Vsupply=12V 1.1 mA

Typical Current Drain (0 to 10 V Mode)

No load, Vout=0, Vsupply=12V 21 mA
No load, Vout=fullscale, Vsupply=12V 28 mA
With load, Vsupply=12V 28 mA + (2.4)(load)
Power Down Mode, Vsupply=12V 1.1 mA


Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.


Product Compatible Note
CR1000 (retired)
CR200X (retired)
CR216X (retired)
CR3000 For the CR3000, SDMs are connected to the ports labeled SDM-C1, SDM-C2, and SDM-C3.
CR5000 (retired) For the CR5000, SDMs are connected to the ports labeled SDM-C1, SDM-C2, and SDM-C3.
CR800 (retired)
CR850 (retired)
CR9000X (retired)


Product Compatible Note

Additional Compatibility Information

Data Logger Considerations

Up to 15 SDM devices can be connected to a single data logger.

Power Supply

It may be convenient to use the data logger’s batteries to power the SDM-AO4A, but consideration must be given to the SDM-AO4A’s continuous current drain (11 mA in ±5 V mode or 21 mA in 10 V mode). The data logger’s alkaline batteries can power one SDM-AO4A for less than a month, and therefore these batteries are not recommended for continuous long-term operation. The data logger’s sealed rechargeable batteries, float charged by an ac supply or solar panel, typically can be used for long-term operation.

The SDM-AO4A may also be powered from an external 12 Vdc source, independent from the data logger batteries. The low side of this external 12 Vdc source needs to be connected to data logger ground and not directly to earth ground.

Enclosure Considerations

The SDM-AO4 requires a desiccated, non-condensing environment; a Campbell Scientific enclosure is recommended. The SDM-AO4A has built-in keyhole flanges for mounting to the backplates of Campbell Scientific enclosures. Grommets and screws are provided to attach the flanges/bracket to the backplate of our enclosures.

FAQs for

Number of FAQs related to SDM-AO4A: 4

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  1. To get continuous analog outputs, either the SDM-AO4A (four channels, non-isolated, voltage only) or the SDM-CVO4 (four channels, isolated, voltage or current) is needed. Multiples of those devices can be used to acquire more outputs.
  2. The CR1000 does not have any continuous analog outputs. It has three excitation channels that are momentarily turned on during measurements. Use the SDM-AO4A for proportional control or driving strip charts.
  3. For the CR1000, to get continuous analog outputs, an SDM-AO4A (4-channels, non-isolated, voltage only) or an SDM-CVO4 (4-channels, isolated, voltage or current) is needed. Multiples of these devices can be used to get more outputs.  For single channels of output, some third-party devices can be used.

  4. Yes. The CR3000 and CR5000 have two native Continuous Analog Output channels. The SDM-AO4A (voltage) or SDM-CVO4 (voltage or current) can also be used.

Case Studies

Flemish Coast: Pile Monitoring
Cofely Fabricom NV/SA (GDFSuez) has utilized Campbell Scientific equipment on numerous projects in both more

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